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NCT Number: NCT07552844

Effects of 8-Week CrossFit-Based Concurrent Training on Fitness, Body Composition, and Psychological Outcomes in Schoolchildren

This study examines the effects of an 8-week CrossFit-based concurrent training program in boys and girls aged 7 to 11 years, comparing an experimental group (n=15) with a control group (n=15). The aim is to assess changes in strength, cardiorespiratory fitness, body composition, and psychological variables such as anxiety, stress, and self-esteem, using field-based physical tests (CMJ, Course Navette, handgrip strength, etc.) and validated questionnaires. The study follows a randomized controlled trial design with pre- and post-intervention assessments. The experimental group will complete two weekly CrossFit sessions adapted for children, while the control group will maintain their usual routine without structured physical training. The hypothesis states that the intervention will significantly improve both physical performance and psychological well-being in the experimental group compared to the control group.

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Key information

Conditions

Children Anxiety Disorders Body Composition CrossFit Mental Disorders Physical Fitness Psychology, Child

Age range

7 year–11 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

IMIBIC

Córdoba, 14004, Spain

About this study

This study is a randomized controlled trial designed to examine the effects of an 8-week CrossFit-based concurrent training program on both physical fitness and psychological well-being in school-aged children (boys and girls aged 7 to 11 years). The sample will be drawn from a primary school in Córdoba (Spain) and will be randomly assigned to either an experimental group (n=15) or a control group (n=15).

The experimental group will participate in a supervised CrossFit Kids program, consisting of two weekly sessions of 50 minutes each. These sessions will include functional, age-appropriate high-intensity exercises structured into four parts: warm-up (mobility and games), strength work (technical and developmental exercises), metabolic conditioning (METCON), and a final cool-down or game-based activity. The control group will continue with their usual daily routine without any structured physical training during the intervention period.

The study will assess changes in physical fitness variables, including muscular strength (countermovement jump, handgrip strength, standing long jump, and medicine ball throw), cardiorespiratory fitness (Course Navette test, burpees, abdominal endurance tests, and step tests), and body composition indicators such as BMI, waist circumference, and waist-to-height ratio. In addition, psychological outcomes will be evaluated using validated instruments measuring state and trait anxiety (State-Trait Anxiety Inventory), daily stress (Children's Daily Stress Inventory) and self-esteem (Rosenberg Self-Esteem Scale).

Measurements will be taken before and after the intervention to compare intra- and inter-group changes. The study also explores potential relationships between improvements in physical fitness and psychological outcomes.

The main hypothesis is that participation in the CrossFit-based concurrent training program will lead to significant improvements in strength, endurance, body composition, and psychological well-being (reduced anxiety and stress and improved self-esteem) compared to the control group, highlighting the potential of this training approach as an effective and comprehensive intervention for children.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age: 7-11 years.
  • Students enrolled at CEIP Pablo García Baena (Córdoba).

For the experimental group:

  • Availability to attend the Triple XXX Box (Polígono Pedroches, C. los Alfareros, Parcel 119, 14014 Córdoba), where both assessments and training sessions will be conducted.
  • Availability to attend training sessions twice per week for the 8-week intervention period.
  • No participation in extracurricular physical activity prior to the start of the CrossFit program.

For the control group:

No participation in extracurricular physical activity. Informed consent signed by parents or legal guardians. No medical, psychological, or behavioral contraindications that would prevent participation in physical activity.

Exclusion criteria

  • Children with musculoskeletal injuries, diseases, or medical, psychological, or behavioral conditions that limit physical activity or interfere with the assessment of outcomes.
  • Inability or anticipated difficulty in regularly attending training sessions.
  • Refusal of parents or legal guardians to provide informed consent.

Treatment and study plan

CrossFit training

Other

The experimental arm will receive an 8-week concurrent training intervention based on a CrossFit program adapted for children, with a frequency of two 50-minute sessions per week. Each session will be structured into a warm-up (mobility exercises and games), strength training (technical and functional exercises), metabolic conditioning (METCON), and a cool-down phase. The program will be supervised by qualified professionals to ensure safety and proper execution of the exercises.

Other names: Body composition, Psychological Outcomes

Primary outcomes

  1. Countermovement Jump Test (CMJ) - Explosive Strength Test

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    The countermovement jump (CMJ), is used to assess explosive strength of the lower limbs. In this test, participants begin in an upright standing position with their hands placed on their hips to avoid arm swing contribution. They are instructed to perform a maximal vertical jump following a rapid downward countermovement, descending to approximately 90° of knee flexion, and then immediately jumping as high as possible.

  2. Standing Long Jump

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    This test consists of performing a horizontal jump using both feet simultaneously, starting from the same level. A preliminary jump is not allowed. The maximum horizontal distance achieved is recorded, measuring from the starting line to the rearmost point of the shoe closest to that line. Upon landing, the participant must maintain balance and remain stationary.

  3. Medicine Ball Throw Test

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    The medicine ball throw test (2 kg) is performed from an upright standing position, holding the ball with both hands above the head. Participants are required to throw the ball as far as possible by performing a flexion-extension movement of the legs, with or without trunk extension.

  4. 20 m Shuttle Run Test (Course-Navette)

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    In the 20 m shuttle run test, participants run back and forth between two lines set 20 m apart, with progressively increasing speed. The initial running speed is 8.5 km/h and increases by 0.5 km/h every minute. Each increase in speed corresponds to a new level.

  5. Plank Hold Time

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    The plank protocol requires participants to maintain a static prone position, with only the forearms and toes in contact with the ground. Proper form requires feet together with toes pointing downward, elbows positioned under the shoulders at forearm width, and hands clasped together on the floor.

  6. Burpess

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    To perform a burpee, participants begin with feet shoulder-width apart and lower into a squat by bending the knees. They then place their palms on the floor and jump back into a plank position with arms extended, ensuring hands face forward, feet rest on the toes, and the back remains straight. Next, they perform a push-up by bending the elbows and returning to the plank position. Then, they jump forward into a squat position, keeping hands on the ground, hips lowered, thighs parallel to the floor, and knees positioned between the elbows. Finally, they jump vertically from the squat position, extending the arms overhead during the jump.

  7. Step Test

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    This test consists of stepping up and down on a platform approximately 30 cm in height, maintaining a constant speed and rhythm.

  8. State-Trait Anxiety Inventory for Children

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    State-Trait Anxiety Inventory for Children is a psychological instrument designed to measure two dimensions of anxiety in children: state anxiety, referring to temporary or situational anxiety, and trait anxiety, which assesses the general tendency to experience anxiety.

  9. Children's Daily Stress Inventory

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    This test aims to assess daily stress in children by evaluating how common experiences, such as school, family, and social issues, contribute to stress levels.

  10. Rosenberg Self-Esteem Scale

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    The Rosenberg Self-Esteem Scale assesses an individual's self-worth through a series of statements reflecting overall self-evaluation.

Secondary outcomes

  1. Body composition

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    Body composition will be assessed using bioelectrical impedance analysis, with particular emphasis on body fat percentage. Measurements will be conducted in accordance with the protocol established by the International Society for the Advancement of Kinanthropometry (ISAK).

  2. Perceived Exertion

    Time frame: Week 1 (Day 1), Week 8 (Day 16)

    Perceived exertion will be measured using a pictorial and verbal category-ratio scale designed for children.

Study contacts

Contact information is provided by the study sponsor or research team.

José Manuel Jurado Castro

CONTACT

[email protected]

+34 957 21 37 00

Sponsors and collaborators

Lead sponsor

Maimónides Biomedical Research Institute of Córdoba

Other

Collaborators

  • Escuela Universitaria de Osuna
  • Universidad de Córdoba

Registry information

Official study title

Effects of an 8-Week CrossFit-Based Concurrent Training Program on Physical Fitness, Body Composition, and Psychological Outcomes in Schoolchildren: A Randomized Controlled Trial Protocol

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Apr 27, 2026
Registry last updated
Apr 30, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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